The Bengals get to pick their uniform first and will most likely pick one of their usual home jerseys - either black or orange.
The Rams designated their blue and bone jerseys as their 'standard' jerseys and the modern throwback (white) jerseys as their alternates.
From this site: [
www.nfl.com]
Los Angeles introduced its alternate top, which it termed the "modern throwback,"... and teams can't wear their alternate jerseys in the Super Bowl. So bone it is.
From this site: [
en.wikipedia.org]
Teams are only permitted to wear alternative jerseys once in playoff games (except the Super Bowl, where teams must wear their standard uniforms)
AlbaNY_Ram